I chose for a Danish layout, because it best suites my needs. QWERTY as for a US International keyboard (the de facto standard in NL) plus the specific signs when typing in Danish(The oh so practical ½ is missing om Textblade's Danish layout BTW ).

Often however, when typing French words I encounter the absence of a ç c-cedille. On a traditional Danish keyboard that is not even possible by overlay; one needs to enter the code by hand.The same problem occurs when typing an ß-ligature in German. When typing Dutch, it would be nice to type an IJ-ligature in one touch, no need to enter the full code (it is not even supported on true NL-keyboards like once it was on typewriters) each and every (and it's frequently used) time or use both I and J as most are used to nowadays. The latter method has consequences for both layout and sorting.

Will Multimap enable us to add those keys to a seemingly empty spot in an existing layout, or even switch existing but unused keys (I may have used a £-sign once or twice in some decades of typing)?

Is the IJ combination a single character? If so can you paste it or type it into the forums?

I can try and put it in a layout in the app and see if it works.

Edit: It appears that any character you can type you can put in a custom map. I was unable to figure out how to paste some Unicode code points into the app, that's likely something that will need to be added, since there are lots of characters that you can use that don't necessarily have a button on mobile keyboards. Less of an issue on desktop.

[Sarcastic mode]The forum is reporting that this post was added 11 hours ago. That makes @central's screenshots late by a factor of over 600. The logical conclusion is that @centralmust be part of @waytools since only they are that proficient at being late on their estimates! [End Sarcastic mode]

Note that I was able to put the ß character in the name of the keymap by copying and pasting from the forum, but I can't paste into the keymap itself. To set it in the keymap I will need to find it on a software keyboard or hook up a hardware keyboard and type Option-S (hardware keyboard mode may not do that on Android, anyway).

This seems like a good place to allow pasting of any character, but I'm sure we'd all rather the keyboard first then that second.

Here's the IJ-character. As you can see, in some typefaces (top-bottom Raleway, Gentium, Courier New, Cutive) the ligature/digraph looks pretty much alike, on the lower two you can clearly distinguish which in that row (all equal) is the I+J, i+j or the ĳ and Ĳ ligature. (here I used the html codes & #307; resp & #306; for the signs. Alternative &ijlig; and &IJlig; not all servers support that alfabetic version though)

Historically it is one letter: ii as a sign for a long i, en_width. The j in ij is just an elegant, ornamental version of the second i in 17th century manuscripts. Only later it turned into a J, persistent even with the introduction of (non-Dutch) typewriters and later computers based on ASCII (neither support the ligature). I still had to learn it as the 25th letter, sorting order shared with y. X - Ĳ-Y - Z

Nowadays the official word list and dictionaries spell it as separate letters I+J and sort as such. In typography the ligature is preferred still though.

They who write in Latin or Hawaiian only may encounter less problems with their surplus on alphabetic signs, than other who miss one.

To get back to @central on the statement, that it might be an OS related problem: I hope so for the Mac users. There is a problem however, one that every Dutch speaker will encounter sooner or later, once or more often, they might not solve that way either, simply because the combination does not exist in Unicode, not as a ĳ-ligature, not as a combined íj-character-set.

Dutch writers often use accents like in 'Zĳ doet het wéér' 'Híj doet het weer' or 'Het dóét het weer' to write the exact location of the stress in the sentence, thus avoiding misinterpretation. As you see in the example, the second vowel of the digraph is accented too. There is no such thing for an ĳ (on capitals it is rarely or not used), nor does the 'j-accent aigu' (a consonant after all and alas not used in any central-european character set) appear in Unicode. And still, both í and j should be accented; the example shows íj unclear as íí would have been, thus screwing up the digraph.For @Axidiel this problem may serve as example, that Ĳ still IS considered one letter / dighraph, even when typed and sorted I+J.

Of course, when handy enough, one could adapt the ligature and/or single j to bear the accent in the most used TrueType or OpenType typefaces (works for printing only, not online for obvious reasons) and save it in the Unicode free spots. If keybinding truly works on OSX and thus iOS keyboards, if iOS supports OpenType fonts, that might be a problem solved. In Android one might get it working per project, but I truly hope for keybinding of a unicode free room symbol on my Textblade instead of a deep search in special symbols each and every use.

FYI: the accented version was not available on Dutch mechanical typewriters either. There was an Ĳ-ligature right of the L, but stress was to be added by pen later on. Lead-type presses used it though.